Prion protein （PRNP） is a ubiquitous membrane glycoprotein whose abnormal self-replicating， misfolded form is widely believed to cause several central nervous system disorders， together known as Transmissible Spongiform Encephalopathies （TSE）. PRNP contains a highly unstable region of five tandem octapeptide repeat. Mutations in PRNP protein’s repeat region as well as elsewhere have been associated with Creutzfeldt-Jakob disease， fatal familial insomnia， Gerstmann-Straussler disease， Huntington disease-like 1， and kuru.
